Power lines along the rear wall of the house

My power is supplied via overhead power lines which run along the rear of the house below the upstairs windows. I'm currently building an extension with a lean-to roof and need to maximize the height where it joins the house to achieve 15 degrees for Velux windows. My plan is to bring the rafters up so that the top of them is at the same height as the top of the cables (the rafters are attached to the wall with a wall plate below that level) and then put my roofing material and flashing over the top effectively enclosing the cables in the top of the roof. the cables would then just enter through the fascia at either end.

Dose anyone know if this is an acceptable approach? When I had a builder around prior to starting the project he just dismissed the cables as 'We'd just build over those' but didn't elaborate how. I've spoken to BC and there is no issue from their perspective.

It is acceptable to run the service cables through the roof of the extension, especially if you don't have to move them. Try to allow a drip loop at the point of entry to allow rainwater to drip off and not penetrate the wall. Take account of the condition of the cable, if it is a new PVC single round type, it will move easily, but if it is 2 cables side by side with a cloth type covering, they will be old and best not moved. Talk to your REC about the cables first, they may move them FOC.

Under no circumstances would I build over or alter the rec's cables. They are not yours and if someone puts a nail through them before the cut out then it will take out the sub-station. I would contact the rec and get your cut out moved to a more suitable location.

They must be visible and accessable.
Contact the DNO, if you are lucky and only the cable needs moving you may only be charged for re-clipping which around my way is £13 per m (I think).
These conductors are not rcd protected and the ocpd is likely to be rated at a few hundred amps so not the sort of thing you want to take chances with

Im no tradesperson but we've just had the exact same issue with knocking down a lean to before building a new extension, The lean to had been built over the cable but the cable was still accessible just not unless you could get inside the lean to. We had to get in touch with Western power and they moved the line. They said that all parts of the cabling MUST be accessible without difficulty to them at all times. They were going to charge us £1000 for the privilege of moving the electric supply 6 meters towards the main supply cable, however I found out from our new neighbours (us being the new people) that the power line serving the 4 properties, went bang last year and so was scheduled for replacing, so I contacted again and managed to get it hurried along, we just replaced the elec box and they connected in less than 2 weeks. obviously yours isn't going to have the same ending, but I assume the cable access issue is probably the same for all electricity suppliers?

Thanks for all of your replies. You all appear to be talking about contacting regional suppliers but as far as I know all power cabling is owned and managed by UK Power Networks (who I have contacted and will be arranging an inspection with to advise me)?

As sated earlier, running in the roof space if you don't move them or nail through them will be OK. If the DNO have issues with this then I would suggest that they come and move them, but for free. They have been given wayleave by your predecessor to run the cables, but it is still your property and you have the final say on who puts what where on it. This is not a silly case of the cables being unsightly, but a serious concern that the building may affect the cables. I do not think it is unreasonable to ask for a re route at no charge. A refusal would indicate the DNO is accepting your build over proposal.

A refusal would indicate the DNO is accepting your build over proposal

Click to expand...

orthat they are under no obligation to re-route.
OP, you asked a sensible question. However this question should be addressed to the DNO. If approached correctly they could well be very amenable, but covering supply cables contravenening ESQCR regs could end up with the threat of disconnection of supply plus remedial costs

Just an update in case anyone else finds this thread and want's to know the outcome. I had UK Power Networks out to look at my build and have been advised that it's fine to build over the cables as long as they don't get moved (they are quite old now and probably brittle).

To recap, the cables will be above the wall plate with the rafters stopping short to give a small void under the flashing where the cables will be. You can see the cables below the upstairs windows in this photo.

Of course it is not ok. It is stupid dangerous and ignorant. The DNO have every right to disconnect the supply
orthat they are under no obligation to re-route.
OP, you asked a sensible question. However this question should be addressed to the DNO. If approached correctly they could well be very amenable, but covering supply cables contravenening ESQCR regs could end up with the threat of disconnection of supply plus remedial costs

Click to expand...

I have seen it done on more than one occasion, not the best practice I agree, but it happens and the DNO have routed them there.